ThreadLocal.h

//// ThreadLocal.h//// $Id: //poco/1.3/Foundation/include/Poco/ThreadLocal.h#1 $//// Library: Foundation// Package: Threading// Module: Thread//// Definition of the ThreadLocal template and related classes.//// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.// and Contributors.//// Permission is hereby granted, free of charge, to any person or organization// obtaining a copy of the software and accompanying documentation covered by// this license (the "Software") to use, reproduce, display, distribute,// execute, and transmit the Software, and to prepare derivative works of the// Software, and to permit third-parties to whom the Software is furnished to// do so, all subject to the following:// // The copyright notices in the Software and this entire statement, including// the above license grant, this restriction and the following disclaimer,// must be included in all copies of the Software, in whole or in part, and// all derivative works of the Software, unless such copies or derivative// works are solely in the form of machine-executable object code generated by// a source language processor.// // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER// DEALINGS IN THE SOFTWARE.//#ifndef Foundation_ThreadLocal_INCLUDED#define Foundation_ThreadLocal_INCLUDED#include "Poco/Foundation.h"#include <map>namespace Poco {
00050class Foundation_API TLSAbstractSlot /// This is the base class for all objects /// that the ThreadLocalStorage class manages.{
public:
TLSAbstractSlot();
virtual ~TLSAbstractSlot();
};
template <class C>
00061class TLSSlot: publicTLSAbstractSlot /// The Slot template wraps another class /// so that it can be stored in a ThreadLocalStorage /// object. This class is used internally, and you /// must not create instances of it yourself.{
public:
TLSSlot():
_value()
{
}
~TLSSlot()
{
}
C& value()
{
return _value;
}
private:
TLSSlot(constTLSSlot&);
TLSSlot& operator = (constTLSSlot&);
C _value;
};
00090class Foundation_API ThreadLocalStorage /// This class manages the local storage for each thread. /// Never use this class directly, always use the /// ThreadLocal template for managing thread local storage.{
public:
ThreadLocalStorage(); /// Creates the TLS.
~ThreadLocalStorage(); /// Deletes the TLS.TLSAbstractSlot*& get(constvoid* key); /// Returns the slot for the given key.staticThreadLocalStorage& current(); /// Returns the TLS object for the current thread /// (which may also be the main thread).staticvoid clear(); /// Clears the current thread's TLS object. /// Does nothing in the main thread.private:
00114typedef std::map<const void*, TLSAbstractSlot*> TLSMap;
TLSMap _map;
friendclass Thread;
};
template <class C>
00123class ThreadLocal /// This template is used to declare type safe thread /// local variables. It can basically be used like /// a smart pointer class with the special feature /// that it references a different object /// in every thread. The underlying object will /// be created when it is referenced for the first /// time. /// See the NestedDiagnosticContext class for an /// example how to use this template. /// Every thread only has access to its own /// thread local data. There is no way for a thread /// to access another thread's local data.{
typedefTLSSlot<C>Slot;
public:
ThreadLocal()
{
}
~ThreadLocal()
{
}
C* operator -> ()
{
return &get();
}
00153 C& operator * () /// "Dereferences" the smart pointer and returns a reference /// to the underlying data object. The reference can be used /// to modify the object. {
returnget();
}
00161 C& get() /// Returns a reference to the underlying data object. /// The reference can be used to modify the object. {
TLSAbstractSlot*& p = ThreadLocalStorage::current().get(this);
if (!p) p = newSlot;
returnstatic_cast<Slot*>(p)->value();
}
private:
ThreadLocal(constThreadLocal&);
ThreadLocal& operator = (constThreadLocal&);
};
} // namespace Poco#endif // Foundation_ThreadLocal_INCLUDED